Abstract
Laser-Doppler measurements are reported of the flow around a square cross section cylinder placed at various heights (Y 0) above a plane channel wall for a Reynolds number Re H = 1.36 × 104.The thickness of the turbulent boundary layer on the channel wall at the obstacle position, but with it removed from the water tunnel, was equal to 0.8 H, being H the square obstacle height and the free stream turbulence intensity was 6%. The periodic character of the flow in the near wake was characterized by measurements of turbulence spectra in the range 0≤ Y 0/H ≤3.3 and the results revealed that regular vortex shedding was suppressed for a gap height less than 0.35 H. Detailed results of time averaged mean flow properties, turbulence intensities and Reynolds stresses revealed the structural differences of the near wakes with and without vortex shedding for Y O = 0.5 and Y O = 0.25 respectively.
Similar content being viewed by others
Abbreviations
- R e :
-
Reynolds number Re = U 0 H/v
- H :
-
Square obstacle height
- Y :
-
Normal coordinate
- Y 0 :
-
Gap distance between the plane wall and obstacle face
- C f :
-
Skin friction coefficient
- k :
-
Turbulent kinetic energy
- u τ :
-
Friction velocity
- δ :
-
Turbulent boundary layer thickness
- y + :
-
Non-dimensional log law coordinate
- X r :
-
Separated flow length behind the obstacle
- U :
-
Mean axial velocity
- V :
-
Mean radial velocity
- u′2 :
-
Axial turbulent stress
- ν′2 :
-
Normal turbulent stress
- u′ ν′ :
-
Turbulent shear stress
- U 0 :
-
Mean bulk velocity
- E :
-
Power spectrum energy
- f :
-
Predominant frequency
- h :
-
Distance between inner shear layers behind the obstacle
- s :
-
Distance from the wall to the shear layer behind the obstacle
- C D :
-
Drag coefficient
References
Adrian, R. J.; Yao, C. S. 1985: Power Spectra of fluid velocities measured by laser doppler velocimetry, ASME, Winter Annual Meeting, Miami Beach, Florida, November 17–22
Bearman, P. W.; Graham, J. M. R. 1980: Vortex shedding from bluff bodies in oscillatory flow: a report on euromech 119. J. Fluid Mechanics 99, 225–245
Bearman, P. W.; Zdravkovich, M. M. 1978: Flow around a circular cylinder near a plane boundary. J. Fluid Mechanics, 89, 33–50
Calvert, J. R. 1967: Experiments on the flow past an inclined disk. J. Fluid Mechanics 29, 691–703
Dimaczek, G.; Tropea, C.; Wang, A. B. 1989: Turbulent flow over two-dimensional, surface mounted obstacles: plane and axisymmetric geometries. 2nd European Turbulence Conference, Berlin, H. H. Fernholz; H. E. Fiedler, Eds. 114–121
Durão, D. F. G.; Heitor, M. V.; Pereira, J. C. F. 1986: A laser anemometer study of separated flow around a squared obstacle. Laser anemometry in fluid mechanics III (ed. Adrian, R. J. et al.), LADOAN, Lisbon, Portugal, 227–243
Durão, D. F. G.; Heitor, M. V.; Pereira, J. C. F. 1988: Measurements of turbulent and periodic flows around a square cross-section cylinder. Experiments in Fluids 6, 298–304
Durão, D. F. G.; Laker, J. R.; Taylor, A. M. K. P.; Yanneskis, M. 1982: Operation and performance of the fluids section FSO2 frequency counter. Imperial College, Mech. Eng. Dept. Report
Edwards, R. V.; Jensen, A. S. 1983: Particle-sampling statistics in laser anemometry: sample-and-hold and saturable systems. J. Fluid Mechanics, 133, 397–411
Everitt, K. W. 1982: A normal flat plat close to a large plane surface. Aeronaut. Q., 33, 90–103
Good, M. C.; Joubert, P. N. 1968: The form drag of two-dimensional bluff plates immersed in the turbulent boundary layers. J. Fluid Mechanis, 31, 547
Heitor, M. V.; Laker, J. R.; Taylor, A. M. P. K.; Vafidis, C. 1984: Instructions for the FS “model 2” doppler frequency counter. Imperial College, Mech. Eng. Dept., Report. FS/84/10
Kamemoto, K.; Oda, Y; Aizawa, M. 1983: Characteristics of the flow around a bluff body near a plane surface. Trans. JSME, 49, 2929–2936
Kamemoto, K.; Yosaku, O.; Aizawa, M. 1984: Characteristics of the flow around a bluff body near a plane surface. Bulletin JSME, 27, 1637–1643
Kiya, M.; Matsumura, M. 1988: Incoherent turbulence structure in the near wake of a normal plate. J. Fluid Mechanics, 190, 343–356
Lee, B. E., 1975: The effect of turbulence on the surface pressure field of a square prism. J. Fluid Mechanics, 69, 262–282
Mair, W. A.; Maull, D. J. 1971: Bluff bodies and vortex shedding: a report on euromech 17. J. Fluid Mechanics, 45, 209–224
McKillop, A. A.; Durst, F. 1986: A laser anemometry study of separated flow behind a circular cylinder. Laser Anemometry in Fluid Mechanics II (ed. Adrian, R. J. et al.), LADOAN, Lisbon, Portugal, 329–346
Okagima, A. 1982: Strouhal numbers of rectangular cylinders. J. Fluid Mechanics, 123, 379–398
Schulte, H.; Rouvé, G. 1986: Turbulent structures in separated flow. 3rd symp. on appli. of laser anemometry to fluid mechanics, Lisbon, Portugal
Tanigushi, S.; Miyakoshi, K.; Dohada, S. 1983: Interference between plane wall and two-dimensional rectangular cylinder. Trans. JSME, 49–447, 2522–2529
Tanigushi, S.; Miyakoshi, K. 1990: Fluctuating fluid forces acting on a circular cylinder and interference with a plane wall, effects of boundary layer thickness. Exp. Fluids, 9, 197–204
Taylor, A. M. P. K.; Whitelaw, J. H. 1984: Velocity characteristics in the turbulent near wakes of confined axisymmetric bluff bodies. J. Fluid Mechanics, 139, 391–416
Unal, M. F.; Rockwell 1987: On vortex formation from a cylinder. Part 1. The inital instability. J. Fluid Mechanics, 190, 491–512
Unal, M. F.; Rockwell 1987: On vortex formation from a cylinder. Part 2. Control by a splitter-plate interference. J. Fluid Mechanics, 190, 513–529
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Durão, D.F.G., Gouveia, P.S.T. & Pereira, J.C.F. Velocity characteristics of the flow around a square cross section cylinder placed near a channel wall. Experiments in Fluids 11, 341–350 (1991). https://doi.org/10.1007/BF00211788
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00211788